Objective        To observe ultrastructural changes of programmed cell death (PCD) during nephron development in mice.       Methods       Light microscopy

transmission electron microscopy

TUNEL method and immunohistochemical assay were used to observe programmed cell death of the nephrons in mouse kidney at embryonic days 12

14

16

and 18.       Results       There were 3 types of PCD found in the development of mouse nephron. They were apoptosis

necroptosis and paraptosis. TUNEL positive cells were increased gradually and reached peak level at embryonic day 18 [(29.45±3.34)%

P0.05]. The expression of Bcl-2 and Bax was increased

and peaked at embryonic day 18 too （80.52±4.06 and 33.67±3.42

P0.05).       Conclusion       There are obvious different changes of PCD among different regions during nephron development in mouse. In the cell death we observed

apoptosis is most common

and necroptosis and paraptosis are also seen.